Field of the Invention
The present invention relates to a toner used to form a toner image through the development of an electrostatic latent image that has been formed by a method such as electrophotography, electrostatic recording, and toner jet recording systems. The present invention further relates to a method for producing a toner.
Description of the Related Art
Lower energy consumption and improved toner performance have been required of printers and copiers in recent years. Specifically, there is demand to bring about toner softening at lower temperatures, but this cannot be achieved with an approach that simply causes toner softening due to the necessity at the same time to maintain the high-temperature storability. Toner that incorporates a crystalline resin has been investigated to respond to this problem. Crystalline resin has little effect on the high-temperature storability of toner because it is crystallized at room temperature, and can bring about toner softening due to a viscosity drop upon melting.
Japanese Patent Application Laid-open No. 2006-106727 proposes a toner in which lamellar crystals of a crystalline polyester are present in the surface layer and the interior of the toner.
At the same time, ever higher speeds are being required of printers and copiers. The stress applied to the toner is enhanced when the developing system is sped up, and this then requires a toner that is more stress resistant and that exhibits an excellent strength. Toners having a core-shell structure have been investigated in order to address this problem without impairing the aforementioned low-temperature fixability.
Japanese Patent Application Laid-open No. 2012-255957 proposes a toner having a core-shell structure, which contains a crystalline polyester and a styrene-acrylic resin as binder resins.
It is stated in Japanese Patent Application Laid-open No. 2011-197192 that, for a toner in which polyester resin is the major component, the compatibility between the shell material and crystalline polyester is low.